De-share the Handler struct in core API (#105979)

* De-share the Handler struct in core API

An upcoming PR adds a handler that only applies on one of these paths.
Having fields that don't work seems bad.

This never should have been shared.  Lifecycle hooks are like a "write"
while probes are more like a "read". HTTPGet and TCPSocket don't really
make sense as lifecycle hooks (but I can't take that back). When we add
gRPC, it is EXPLICITLY a health check (defined by gRPC) not an arbitrary
RPC - so a probe makes sense but a hook does not.

In the future I can also see adding lifecycle hooks that don't make
sense as probes.  E.g. 'sleep' is a common lifecycle request. The only
option is `exec`, which requires having a sleep binary in your image.

* Run update scripts

pkg/kubelet/container/helpers.go

@@ -39,7 +39,7 @@ import (
 
 // HandlerRunner runs a lifecycle handler for a container.
 type HandlerRunner interface {
-	Run(containerID ContainerID, pod *v1.Pod, container *v1.Container, handler *v1.Handler) (string, error)
+	Run(containerID ContainerID, pod *v1.Pod, container *v1.Container, handler *v1.LifecycleHandler) (string, error)
 }
 
 // RuntimeHelper wraps kubelet to make container runtime